Which visa

Hello there, I'm hoping that someone out there can help me make senseout of which visa I should apply for. My situation is a littlecomplicated. I am living in England with my partner of 4 1-2 years who is anAustralian national. We intend to get married at some point in thefuture. However for the duration of our relationship I have beenlegally married to someone else and am currently starting the processof applying for a divorce. I have been separated from my husband forwell over 6 years but we just haven't formalised things by getting adivorce. I am a teacher by profession and have just completed my NQT year. Teaching is worth 60 points and according to the points calculator Ihave over 120 points in total. However I am 29 years old and will turn30 this September (meaning my points will decrease). My boyfriend really wants to go back to Oz by this December but ourproblem is which visa I should apply for and how long it will take. As far as I can see, the options are: prospective marriage; a workingvisa; a working holiday visa. We are tempted to go for the working holiday visa and then try to sortthings out when we get there.